CONCORD, N.H. – New Hampshire’s historic resistance to a personal income tax would no longer be left to politicians to uphold if a proposed prohibition against the tax is enshrined in the state constitution.

The House votes Wednesday on a constitutional amendment that would bar any new tax on personal income. Supporters say the amendment would not affect existing taxes but would stop lawmakers from levying new taxes directly or indirectly on someone’s income regardless of its source.

Opponents object that the proposed constitutional change would handcuff future legislatures dealing with changing economic conditions.

New Hampshire is one of nine states that does not tax personal income, although it taxes interest and dividends. New Hampshire and Alaska are the only states without taxes on either personal income or sales.

State Rep. Keith Murphy, R-Bedford, argues residents work hard for their money and “it would be an incredible injustice for the state to demand some portion of that money.”

“The language is very carefully chosen to forbid only new taxes on individual income. Existing taxes on income, such as the interest and dividends tax, will be unaffected unless first repealed,” he wrote in the House calendar in support of its passage.

But state Rep. Mary Cooney, D-Plymouth, said the amendment leaves too much room for interpretation as to what is a new tax or just an increase to an existing one.

The amendment would need support from three-fifths of the House to pass to the Senate, where the same margin is needed to place it on the November ballot.

Taking an anti-income-tax pledge has been a ritual in gubernatorial elections in New Hampshire for years. Candidates who refused to vow to veto income and general sales taxes have, with one exception, been defeated.

The ritual of taking the pledge began with Gov. Wesley Powell, a Republican first elected in 1958.

Republican Gov. Meldrim Thomson elevated it to a political sacrament in the 1970s with his slogan, “Ax the Tax.” For years it was political suicide for any gubernatorial candidate to even entertain the possibility of a broad-based tax.

Gov. Jeanne Shaheen, a Democrat, refused to take the pledge when she ran successfully for re-election to a third term, but took it before winning her first two terms.

Current Gov. John Lynch, a Democrat, took the pledge to veto sales and income taxes before winning his four terms.